Problem:
In a Planning Analytics (TM1) environment where native security is used, you get a error when you try to add content to workspace from the PA databases on left side of screen.

Error Message:
unable to fetch data for content tree. Session can not be established for server: BUDGET 401 (Unauthorized) (“errorMessage”.””.”query”.”https://…..

Possible Solution:
Log out from Workspace
Go into TM1 Architect.
Set a password for all users, do not use blank (empty) as a password. That will not work for workspace. Also ensure that the ADMIN account have a password like apple.

After the user have a password set, exit TM1 Architect and surf to Planning Analytics Workspace again.